David Weinberg of the Israeli hospital treating Sharon said he remains in critical condition.

The 85-year-old ex-general has been in a coma and connected to a respirator for eight years since suffering a stroke in 2006 while in office. In the last week, function of his key bodily organs has worsened, according to the hospital.

Sheba Medical Center said Sharon is now surrounded by family. His family has said in previous reports that Sharon sometimes opens his eyes and moves his fingers, but that his kidneys and other key bodily organs are in decline.

Little information has been available to the public about his condition over the years. Anyone who goes into Sharon's room has their cellphones taken away, said Judy Siegel-Itzkovich, editor at The Jerusalem Post.

Last year, an Israeli medical team found Sharon's brain had "robust activity" in response to pictures of his family and a recording of his son's voice. But these findings do not definitively indicate consciousness, said Dr. Nicholas Schiff, neurology and neuroscience professor at Weill Cornell Medical College, who has studied brain activity in comatose patients but was not involved in Sharon's tests.

Research is ongoing into just how much consciousness is associated with certain brain activity, Schiff said.

"There's a lot of variance in structural brain injury," he said.

The kind of stroke Sharon suffered was a hemorrhagic stroke, which means a blood vessel bursts and "liberates blood in the brain tissue," said Dr. Steven Zeiler, director of the stroke research at John Hopkins Bayview Medical Center. Zeiler has not treated Sharon.

All strokes are not created equal and it depends on where the damage is in the brain, he said. Given the length of time Sharon has been in a coma, Zeiler said, "It's not the brain bleed that will kill him. It's the body not being able to care for himself."